Just a word of warning -- that page of schedules hasn't been updated since April 2009.
For the most up to date schedules, here are some links:
a) Maya Island Air, http://www.mayaregional.com/
b) Tropic Air, http://www.tropicair.com
Here's a link to the most up to date schedule for the James Bus Line. Thanks to Ian & Kate at Hickatee Cottages for keeping this up to date:https://www.hickatee.com/belize_bus_times.html
By Water Taxi
More thanks to Kate & Ian:https://www.hickatee.com/punta-gorda-water-taxi.html